Sheet metal nut



Feb. 4, 1941.

G. A.l TINNERMAN SHEET METAL NUT Filed Jan. 7, 19:59 2 sheets-sheet 1 3 wu a/rvbO/t/ @50H55 AWN/VERMA/v Feb- 4, 1941 G. A. TINNERMAN 2,230,916

SHEET METAL NUT v 2 Sheets-Sheet 2 Filed Jan. 7, 194:59

Patented Feb. 4, 1941 l SHEET METAL NUT George A. Tinnen-man, Rocky River, Ohio, assignor, by mesne assignments, to Tinnerman Products, Inc., Cleveland, Ohio, a corporation of Application January 7, 1939, Serial No. 249,818

4 Claims.

This invention relates in general to improved spring nut fastening' devices designed for use with cooperating bolt or stud fastenings and adapted to be embodied in numerous installations in lieu of screw threaded nuts and the like as a means for easily and quickly securing the parts of an assembly under spring tension in fixed, rigid relation against accidental dis-` lo l placement or unintentional removal.

The present application claims the invention inthe new and improved structure of the spring nut devices per seas fasteners of general utilq ity, while a copending divisional application Serial Number 373,501, filed January 7, 1941, claims o the invention residing in the structure of the improved forms of bolt or stud fastenings as constructed for special coaction with such spring nut devices in the manner of combined, cooperating spring nut and stud fastening members for providing `a locking but releasable substantial spring coupling securing means having an automatic, self-tightening action, and with said fastening members being readily separable to permit the parts secured thereby to be disassociated and resecured as often as` may be necessary or desirable. l

More particularly, the present invention is directed to an improved spring fastening means of the type wherein a spring nut is expeditiously connected to a cooperating bolt fastening by a simple pressing operation thereon or by a substantial axial straight thrust of the bolt fastening to operative fastening engagement with the spring nut in providing a securing means in which the fastening members may not be separated from applied fastening position except by asuitable, generally predetermined force .on the bolt or substantial pull on the spring nut.

As shown in a number of my prior patents, various types of spring nut devices are designed to provide highly practical, substantially locked fastening installations employing the well known common threaded bolts or screws. Generally, such fastening members cannot be removed except by the usual relative rotary movement to separate the thread engaging elements thereof and this not only involves an objectionable, time consuming'procedure but often results in a deformation and mutilation of the thread engaging elements of the spring nut beyond further ecient and satisfactory use.

Many installations require a spring nut fastening having positive locking characteristics and otherwise capable of providing a rigid, tightened assembly of the parts secured under spring tension, yet which is operative to eiIect an easy, quick release of the fastening members in a minimum `of time and effort. One 0f the primary objects of the present invention is to provide a spring nut fastening means which may be embodied in practically any installation to supplant the usual nut, threaded bolt and lock washer assembly, and which will function in a manner to permit aneasy, quick release and'r ready separation from its cooperating bolt fastening without becoming mutilated or distorted such that the same may be frequently removed and again employed in the same or similar installation any number of times over a. long period of use.

Another principle object of the invention is to provide an improved fastening means of this character for positively securing a member to a supporting part in an Ainstallation and which will permit of a ready detachment of the fastening members by a relatively simple operation without in any way damaging the parts secured -or the fastening means such that the y installation may be mounted and dismounted as necessary any number of times without diminishing the efficiency thereof. 4

Still another object of the invention is to provide an improved spring nut fastening means which may be embodied in self-sustaining relation in various installations comprising Parts to be releasably secured, and also in structures in whichA one of the parts so secured is not conveniently or readily accessible from the reverse side thereof in what is known as a blind location.

Further objects and ladvantages and other new and useful features in the construction, arrangement and general combination of parts of the invention will be readily apparent to' those skilled in the art as a'description thereof proceed-s with. respect to the accompanying drawings in which like reference characters designate like parts throughout the same, and in which:

Fig. 1 is a perspective of one form of the improved spring nut fastening device of the invention comprising a generally concave base when 'normally untensioned;

Fig. 2 is a fragmentary perspective of the shank of a form of bolt fastening which may be employed with vthe spring nut shown in Fig. 1; l

Fig. 3 is a sectional view of an installation comprising superposed apertured parts to be secured by the spring nut and bolt fastening members of Figs. 1 and 2; Y

Fig. 4 is a similar view showing the spring' nut as applied to positive fastening engagement with the bolt fastening to secure the parts under spring tension;

Fig. 5 is a top plan of Fig. 4;

Fig. 6 is a section taken on line 6-6 of Fig. 5; Figs. 7 and 8 are sectional and plan views.

corresponding respectively to Figs. 4 and 5 but showing the bolt and spring nut` fastening memshown in position aboutto be applied to the shank of a bolt fastening such as shown in Fig. 10;

Fig. 12 is a view similar to Fig. 11 with the bolt and spring nut in applied fastening `position and represented in section to show in detail the elements providing the positive locked fastening engagement of this form of the improved fastening means;

Fig. 13 illustrates a further embodiment of the invention in which a member secured onto an apertured supporting part is provided with a substantially smooth, plain shank serving as a connecting stud to which a spring nut of the type shown in Fig. 1 is applied for releasably mounting said member in an installation;

Fig. 14 is a bottom plan View of Fig.-13;

Fig. 15 is a perspective of a further form of the spring nut provided with auxiliary securing means for attaching the same in self-sustaining position on a part such as a structural member in a blind location in which the reverse side thereof is inaccessible in a completed installation;

Fig. 16 is a sectional view representing such an installation and in which a member provided with a substantially smooth connecting stud is shown about to be applied in mounted position;

Fig. 17 is 'a view similar to Fig. 16 showing the respective parts in fully assembled relation;

Fig. 18 is a sectional view of an installation of this character employing a grooved bolt fastening for providing a substantially positive locked mounting for a handle or the like on a supporting part;

Fig. 19 is a side view of Fig. 18 showing the initial step in the operation for separating the parts of the installatiomif desired;

Fig. 20 is a sectional view of a further embodiment of the invention in kwhich a bolt fastening comprising a shank having reduced areas is employed for effecting a quick release of the parts secured; y

Fig. 21 isa similar View showing the bolt as rotated substantially ninety degrees to position the shank for ready removal from the spring nut fastening member;

Fig. 22 is a top plan view of Fig. 21;

Figs. 23 to 26 inclusive illustrate various alternate means for attaching the spring nut to the reverse side of a-supporting part in blind locations, for example, Fig. 23 showing a form of the spring nut provided with clip holding elements at either end thereof about to be applied to slots provided in such a supporting part;

il Fig. 24 is a sectionalview showing a completed assembly embodying a spring nut attached to the ,supporting part as illustratedv in Fig. 23; and Q Fig. 25 shows a spring nut attached to a sup-` "v-,fastructural part.

Theun-proved spring nut fastening means per se of the invention, may be provided as integral elements in any sheet metal structural member, or may assume the form of a sheet metal fastening or locking plate usable in the manner of a substantial spring nut. In the latter respect, there is a much wider range and variety of uses and accordingly, it is to be understood that though the description which follows refers to the various embodiments of the fastening means as spring nuts, it is fully contemplated that the essential features and characteristics thereof be embodied as the fastening means in any equivalent structure secured by a bolt or stud fastening device whether a separate shank member or integral connecting stud element or the like.

A spring nut in accordance with the invention may be provided of any size or shape but is preferably formed from an inexpensive, substantially rectangular' section of metal which may be obtained at minimum cost from ordinary sheet metal strip stock without loss or waste of material whatsoever. Any type of sheet metal may be employed but preferably that of a spring metal nature such as tempered spring steel or cold rolled steel having spring-like characteristics. By suitable slitting, bending and forming operations, the sheet metal section comprising the spring Anut is provided with projecting bolt engaging means in the manner of tongues or the like having substantial cam lips formed thereon for frictionally and grippingly engaging the bolt connected thereto in applied fastening position, but permitting a quick, easy release therefrom in a man- 4 through in one direction to applied fastening position in which relation the spring nut is effective to provide a rigid, tightened installation under continuously effective spring tension. In suchapplied fastening position of the bolt and spring nut, any ordinary axial movement of the bolt toward disengagement or removal from the spring nut not only is prevented but also results in a movement of the tongues toward each other in a direction to diminish the space therebetween and otherwise cause the cam lip extremities thereof to even more positively engage the bolt and prevent withdrawal thereof. A

Referring now, more particularly to the drawings, Fig. 1 shows one preferred form of the improved spring nut which is constructed of a plate-like section of spring metal suitably stamped to provide substantial end portions I joined by side or bridge portions 2 between which bolt engaging tongues 4, 5, extend upwardly with their free ends formed into substantial cam lips 6, 'I designed to supply a positive, substantially locked gripping relation Y with the cooperating bolt fastening in applied fastening position and -at the same time, permit an easy quick release therefrom as hereinafter set forth.

'I'he body or base of the locking plate defined by the end and side portions I, 2 is somewhat flexible and is so formed in the stamping operation as to have a pronounced, generally concave Yavisame to fastening position by a substantial axial,

thrust-like motion in a minimum of time and effort and the generally concave body of the device flattened in such fastening poistion thereby xedly securing the fastened parts of an installation under continuously eiective spring tento provide for a positive locked fastening engagement, the bolt fastening shank I0 is preferably formed with opposed grooves or recesses I I, separated by unindented areas I2. Said recesses are provided of course. at suitable predetermined points on the bolt shank in accordance with the combined thickness of the parts secured and present shoulders I3 against which the cam lip extremities 6, 1 of the tongues of the spring nut are designed to abut in providing a rigid, positiye, locked fastening engagement. 'I'he bolt fastening otherwise may be tapered at its leading end to provide a substantial pilot readily introduced between the tongues of the spring nut, while the opposite end thereof is provided with any suitable head having a tool recess I4. t i

From the foregoing, it will be understood tha when the spring nut and bolt fastening just described are employed as the means for securing an installation comprising, for example, superposed partsA, B having aligned apertures, thev shank I0 of the bolt is passed through such apertures from one side thereof to project onto the opposite side thereof Afor operative engagement with the tongues of the spring nut substantially as shown in Fig. 3.

Referring to Figs. 4, 5 and 6 it vwill be appreciated that when the spring nut is applied to the projecting shank of the bolt fastening and pressure exerted in a. substantial axial,thrustlike movement, the yieldable tongues 4, 5 thereof are caused to slide along the bolt. shank to the point at which the end portions I of the generally concave base, contact the adjacent surface of the structural part A. lAt such point, upon continued pressure on the bowed side portions 2 of the spring nut, the said end portions are moved from their initial, normally untensioned position in the generally concave base outwardly and upwardly suiiicient to permit the cam lips 6, 1, of the tongues to snap into the recesses II of the bolt shank in rm, positive substantially locked engagement with the shoulders I3presented thereby to resist any tendency4 toward reverse movement orV withdrawal therefrom. At the same time, the bowed lside portions 2 are elongated such that the generally concave base of the spring nut is tensioned and assumes the position of a substantially flat section Figs. 4 and 6 which, in attempting to assume its initial, normal untensioned concave configuration, naturally tends to transmit a lifting force to the tongues to draw the shank of the bolt axially thereby taking up any clearance in the parts secured and firmly and rigidly securing the same underycontlnuous spring tension in a substantially locked installation.

It has been found that this most effective locking and drawing action of a spring nut to provide a tight, rigid installation is best obtained when the' generally concave base thereof is flattened without any substantial pressure being exerted on the tongue elements themselves; any substantial pressure on the tongues prevents the same from having smooth, sliding engagement with the shank of the bolt fastening on being applied. and also bends the tongues with respect to the generally concave base such that the cam lip extremities thereof are deformed out of position for most eective contact with the shoulders I3 on the shank, whereupon the tongues might have a tendency to slip and permit the spring nut to loosen from applied fastening position in a tightened installation. This application of the spring nut to fastening position is preferably effected by the use of a special tool comprising spaced jawswhich may be fitted to the side portions 2 of-the generally concave base thereof` without materially contacting the tongue eleatten the same and tension the generally concave base of the spring nut with the cam lip extremlties 6, I of the tongues thereof seated in the recesses II of the bolt as best seen in Figs. 5 and 6; and accordingly, when the tool is withdrawn and the attendant pressure removed from the said flattened side portions, the compression therein causes the cam lips of the tongues to positively engage the shoulders I3 of the bolt and simultaneously exert an axial drawing action thereon in providing a locked, tightened installation under continuously effective spring tension.

The positive locked fastening engagement of the bolt and spring nut as shown in Figs. 4 to 6 inclusive may be easily and quickly released by a simple, relative rotation of thefastening mem-` bers substantially ninety degrees, to the general position represented in Figs. 'I to 9 inclusive wherein the cam lip extremities 6, 'I, are forced out of engagement with the shoulders I3 of the bolt fastening and disposed at the unindented areas I2 thereof, in which position the bolt and spring nut may be readily separated by a suitable axial force on the bolt or substantial pull on the spring nut. It will be understood that any such relativeturning movement of the bolt and spring nut, necessarily-spreads the `tongues apart and forces the cam lips 6, 'I to ride out of engagement with the shoulders I3 on the bolt and engage the unindented areas I2 thereof. Thus the bolt and Ispring nut are released from positive locked fastening engagement and the said cam lips are disposed merely in frictional engagement with the bolt in such position as to be readily removed therefrom in the manner aforesaid.

Figs. 10 to 12 inclusive show a further embodiment of the invention in which the spring nut is of the same general character as that described with reference to Figs. 1 to 9 inclusive, but is formed. withJ a substantially at base and employed in a somewhatdilerent manner with the bolt shank to provide the desired spring tension and axial drawing action making for a rigid, tight installation.- As shown in Fig. l0, the bolt shank 20 is formed with grooves 2l providing opposed relatively long cam shoulders 23 separated by unindented areas 22. With the side or bridge portions 3 of the spring nut formed substantially flat as shown in Fig. 11, the tongues 4, 5 are so designed that the caml lip extremities 6, 1 thereof are spaced apart in normal untensioned relation a distance substantially equal to or less than the diameter of the boltbetween the bottomsof the grooves 2|. Accordingly, the fastening members thus provided are easily and quickly connected in fastening engagement simply by pressing the same together such that the entering end of the bolt spreadsthe tongues apart sufficient to seat the vcam lips li,V 'I thereof on the relatively long cam shoulders 23 of the bolt substantially as shown in Fig. l2. In this position, the tongues of the spring nut naturally tend to assume their initial normally untensioned relation and accordingly, cause the cam lips 6, 1 to ride on the relatively long cam shoulders 23 thereby exerting an axial drawing action on the bolt to provide a rigid, tight, substantially locked installation of the parts secured under continuously effective spring tension. The holt and spring nut fastening members. of this form of the invention may be easily and quickly released from such substantially locked fastening engagement in the same general method described with reference to Figs. 7 to 9 inclusive; thus upon a substantially quarter turn relative rotary movement of the fastening members from the position shown in Fig. 12, the cam lip extremities areforced out of engagement with the shoulders '3 of the bolt fastening and disposed at the unlndented areas 22 thereof whereupon the bolt and Vspring vnut may be readily separated by a suitable force on the bolt or substantial pull on the spring nut.

Although the distinct forms of the spring nuts represented4 in Figs. 1 and 11 respectively, are shown in connection with bolt fastenings having grooved shanks, it will be readily appreciated that either form provides an effective highly satisfactory fastening arrangement when employed with a shank which happens to be substantially plain and smooth throughout its length.' Inasmuch as such plain shank elements are the least expensive to provide, they are employed whenever possible on practically any ob- -ject to be secured in an installation. For example, as shown in Figs.v13 and 14, an object 25 of relatively thin cross-section and insufficient thickness to receive a threaded fastener or metallic insert without being exposed, is best provided with fastening means in the manner of an integral connecting shank 26 formedon the underface thereof to project lthrough an aperture in the support C in position for the application thereto of a spring nut preferably of the type shown in Fig. 1. In the applied mounted position of theobject onthe support, the cam lips 6, 1 of the spring nut frictionally and grippingly engage the smooth connecting shank in positive fastening engagement therewith, while the generally concave base thereof exerts an axial pull thereon to draw the object into close ush engagement with the support under continuous spring tension substantially in the manner aforesaid. By virtue of the cam lip arrangement on the tongue extremities the spring nut may be readily released from the stud fastening simply by employing a suitable wedging tool, such as a screw driver, in a manner to cause the cam lips to gradually creep along the connecting shank to finally disengag'e therefrom and permit the spring nut-to be removed.

Fig. 1 5 shows a further form of a spring nut designed for use, for example, in an installation wherein the rear side of a supporting part in an lassembly' becomes inaccessible in a substantially blind location. In such instances, it becomes necessary to provide the spring nut with suitable means whereby the same may be attached to the supporting part and held in proper self sustaining position preparatory to the application thereto of a bolt fastening or other shank member securing an object or cooperating part to the supporting part. Inasmuch as the spring nut is a unitary sheet metal device, a most practical form of such attaching means may be provided in the manner of integral thread engaging elements 21, 23, struck and formed preferably from extended end sections of the spring nut, although similar elements may just as well be provided from widened side portions 3, or the like. A spring nut of this character otherwise includes cam lip formations 6, 1 on the tongues thereof substantially similar to the forms of devices illustrated in Figs. 1 and l1, and accordingly by means of said thread engaging elements 21, 28, the device may be readily attached to the rear side of a supporting partA D byscrews 30, 3|, as shown in Fig. 16 with.the tongues 4, 5, thereof overlying a bolt or stud passage 32 provided in said part'. By this arrangement, practically any bolt fastening may be applied to substantially locked fastening engagement withthe spring tongues by a simple pushing operation taking place entirely from the accessible side of said supporting part. For purposes of illustration, an object 25' such as described with reference to Figs. 13 and 14, comprising a substantially plain connecting shank 26', is shown secured to the supporting part in a completed installation, Fig. 17, with the spring tongues frietlonally and grippingly engaging said shank to retain the object in applied mounted position but capable of being released if desired by suitable reverse axial force on the connecting shank to causel the same to vgfadually Work loose from engagement with the cam lips 6, 1 of the spring ifzongues and eventually become separable thererom.

Figs. 18 and 19 illustrate a further embodiment of the invention in which the general type of spring nut and attaching means therefor shown in Figs. l5 to 17 inclusive, may be employed in a substantially blind location as the means for mounting a knob. handle or like object onto the supporting member D. Such an object 35 may of course assume any desired shape or configuration and is'provided with a projecting bolt fastening 36 xedly secured thereto, for example, by a threaded metallic insert 31. The projecting shank of the bolt fastening is grooved adjacent the free end thereof to provide an annular relatively long cam shoulder 38 operatively engaging the cam lip extremities 6, 'l of the spring nut tongues substantially in the manner described with reference to the form of device shown in Figs. 11 and 12. Since in this embodiment the groove and cam shoulder 38 preferably extend around the entire periphery of the bolt shank, said shank may be applied at random to fastening engagement with the tongues of the spring nut toA mount the knob, handle or other object in any desired position on the supporting part D. In this position the cam lip extremities 6, 1 of the tongues ride on the cam shoulder 38 on the bolt shank in attempting to assume their normal untensioned relation thereby exerting an axial drawing action on the shank to drawthe object secured to close flush engagement with the support under continuously effective spring tension in providing a rigid positive locked mounting which is not subject to displacement or accidental removal.

Referring to Fig. 19, it will be understood that the object thus secured is dismountable from the installation by effecting a release of the bolt shank from the tongues of the spring nut in a relatively simple procedureby which the cam lip extremities', 1 are forced apart sumcient to permit removal ofv the bolt shank therefrom.

This operation of course must usually take place entirely. from the forward, accessible side of the supporting part D and accordingly, by effecting a substantially lateral turning moment on the bolt shank 35 by means of a wedging tool or through suitable force on the object 35, a torque is exerted on the bolt shank to cause the cam.

shoulder 38 to cam against the cam lip tongue extremities 6, 1, transversely thereof and thus gradually spread the same apart until the bolt shank is removable therefrom.

Figs. 20 to 22 inclusive show a still further f embodiment of the invention in which the previously described spring nut comprising attaching means 21, 28 isemployed in a substantially blind or inaccessible location together with a4 form of bolt fastening designed for use where frequent release of the fastening members is required, as in a substantial coupling construction or similar temporary fastening means. Such a bolt fastening 40 may comprise a head having a tool recess 4I and a shank 42 having one or more cutaway portions providing reduced areas, the opposing faces 43 of which are of less spacing than the distance between the cam lip extremities 6, 1 of the spring 4nut tongues. The surfaces 44 however are of full diameter and accordingly such a bolt fastening is admirably suited as the stud fastening for securing a part 45 to supporting member D as shown in Fig. 20, with said surfaces 44 in positive fastening engagement with cam lip 5, 1 of the tongues of the spring nut. If desired, the bolt fastening maybe formed with grooves or ribs presenting shoulders on the surfaces 44 in providing a substantially locked fastening installation substantially as described with reference to' Figs. 11 and 12. In any4 event, the fastening members thus provided are easily and quickly released by a simple, relative rotary movement of the bolt shank substantially ninety degrees to the position shown in Figs. 20 and 21, wherein the faces 43 of the reduced areas thereof are out of contact with the tongues such that the bolt fastening may be easily and quickly removed therefrom and the parts of the assembly readily disassociated.

In the several installations appearing in Figs. 15 to 22 inclusive it is fully contemplated as within the scope of the inventiton that various other means in place of the thread engaging elements 21, 28 be employed for attaching the spring nut to a supporting part in any installation in which it is desired that the same be retained in selfsustaining position prior to the application of the cooperating bolt fastening thereto., In this respect, highly satisfactory arrangements may be provided in the use of rivets, eyelets, spot welding, clip or clasping arms, anchoring prongs or lugs and various related forms of securing means for holding the spring nu't in such self-'sustaining position on the .supporting part.

Figs. 2,3 and 24 show a preferred form of spring means in the manner of substantial clip holding4 arms 50, 5I at either end of the spring nut. i Thus holding arms in slots 53, 54provided cna free edge of the part to clasp the saine on its opposite faces as shown in Fig. 24, thereby holding the spring nut in assembled relation thereon with tongues 4, 5 overlying the passage 5B in position to receive the cooperating bolt fastening. The bolt of course may be similar to any of those shown in the previously described forms of the invention; however, for purposes of illustration, a completed installation is shown embodying the reduced shank type of bolt fastening 4l)V appearing in Figs. 20 to 122 inclusive which secures member 55 to the supporting part E and is designed to effect an easy quick release of the fastening members by a simple quarter turn rotary movement of the bolt shank vout of engagement with the cam lips 6, 1 of the spring nut tongues.

Figs. and 26 show the use of further alternate means for attaching the spring nuts onto similar supporting parts in registration with suitable bolt passages provided therein, Fig. 25

illustrating the application of substantial rivets the spring nuts and provide bolt fastenings having shanks of different lengths such that the Vdevices may be readily adapted to securing various thicknesses of 'materiaL as will be readily understood. In this respect the spring nuts also have an advantageous function inasmuch as they comprise resilient bases carrying yieldable tongues which of courseiiex to a certain degree and thus permit the use thereof with a certain size bolt fastening for securing any of several thicknesses of parts.

It is quite apparent that numerous, advantages are inherent in the improved spring nut constructions of the present invention, one of the foremost of such advantages residing in the provision of cam lips on the tongues, which cam lips in any embodiment of the invention are spaced apart in normal untensioned relation a distance less than that between the diametric points of fastening engagement with the bolt fastening employed therewith, whether a substantially smooth, threadless connecting stud or shouldered bolt shank element or the like. Thus by this arrangement, it has been seen 'that the bolt engaging elements in any form of theimproved spring nut not only providea positive, rigid fastening engagement with the cooperating bolt fastening under continuously effective spring tension, but also'provide for an easy quick release of a bolt and spring nut from` applied fastening l position without in any way deforming, mutilating or otherwise damaging either of the fastening members such that the same may be frequently separated and again fastened together any number of times over a long period of use with freedom from all diiculties. By contrast, practically al1 heretofore known forms of spring nuts not only require a tedious operation for removal but also usually result in a deformation and-mutilation of thefastening members such thatl they are less eillcient and often useless when again employed in the installation from whichithey were removed.

While this invention has been described in detail with specific examples, such examples are intended as illustrations only, since it will be apparent to those skilled in theartthat other rmodiiications in the construction, arrangement and general combination of parts may be deing a base provided with an opening, cooperating yieldable bolt retaining elements provided from the material of said base with the free ends thereof adjacent said opening, said bolt retaining elements terminating in bent portions forming substantial lips on the extremities thereof, said lips defining substantially plane surfaces inclined with respect to the general, planes of the remaining portions of said bolt retaining elements.

2. A sheet metal fastening structure compris.- ing a base provided withan opening, cooperating yieldable stud vsecuring elements provided from the material of said base with the free ends A thereof adjacent said opening, said stud securing elements terminating in bends adjacent said free ends thereof, said bends providing substantial lips on the extremities of said stud securing elements extending outwardly therefrom in the direction away from said base, said lips deiining substantially plane surfaces inclined with respect to the general planes of the remaining portions of said stud securing elements. y

3. A sheet metal fastening structure for use with a cooperating threadless bolt or connecting stud fastening, said sheet metal fastening structure comprising a base and a pair of cooperating bolt retaining elements struck and formed therefrom, said bolt retaining elements terminating in bent portions forming substantial lips having surface engagement with said bolt shank in frictional, gripping relation therewith, said lips being adapted to be spread apart to permit said bolt shank to be disengaged from said bolt retaining elements without mutilation or distortion thereof.

4. A sheet metal fastening structure for use withv a cooperating threadless bolt or connecting stud fastening having a shoulder provided on the sh'ank thereof, said sheet metal fastening structure comprising a generally concave base when normally untensioned and a pair of cooperating bolt retaining elements struck and formed therefrom, said bolt retaining elements terminating in bent portions forming substantial lips having surface engagement with said shoulder on the bolt shank in gripping relation therewith, said generally concave base being adapted to exert an axial drawing action onv the bolt shank through said bolt retaining elements to provide a tightened installation under continuously effective spring tension.

GEORGE A. TINNERMAN. 

